Comparative study of various extraction methods for the quantitative determination of free amino acids from brain tissue

Seven published extraction methods for the quantitative determination of the amino acids of biological fluids and tissues were applied to brain tissue and the experimental data analyzed statistically.     

Comparative effectiveness of different methods for the microbiological study of resected pulmonary tuberculomas

Wide-range microbiological study (bacterioscopy, inoculation, biological assays) of 114 lung tuberculomas excised from 107 patients has revealed a pronounced variability and sharply decreased viability of mycobacterial populations vegetating in caseous foci. Differences in the frequency and character of the detection of Mycobacterium tuberculosis and their altered forms, arising from the use of three above-mentioned methods of microbiological investigation, were noted. Bacterioscopy proved to be more informative with respect to the detection of the bacterial forms of M. tuberculosis. Biological assay was highly sensitive with respect to the L-forms of M. tuberculosis and permitted the detection of the persisting forms of this infective agent, contained in caseous foci and not detected by the method of inoculations. To evaluate the actual state of the mycobacterial population in the focus of tuberculous lesion, the use of a complex of microbiological methods for the detection of typical and biologically altered forms of M. tuberculosis is necessary.     

Diagnosis of tuberculous lymphadenitis by FNAC, microbiological methods and PCR: a comparative study

Despite its usefulness in the diagnosis of tuberculous lymphadenitis, fine needle aspiration cytology (FNAC) faces several limitations, and its sensitivity and specificity are not well established. The diagnostic accuracy and limitations of FNAC were studied in comparison with conventional microbiological methods and polymerase chain reaction (PCR). Sixty patients with lymphadenopathy and a clinical diagnosis of tuberculous lymphadenitis were subjected to FNA. The aspirate was used for cytological examination, Ziehl-Neelsen staining, mycobacterial culture and PCR. PCR was performed using two sets of oligonucleotide primers for Mycobacterium tuberculosis and a single primer for M. bovis species. The results of FNAC, microbiological methods and PCR correlated with the clinical outcome after follow-up for an average period of 24 months. Twenty-five cases (41.6%) were treated and responded well to anti-tuberculosis therapy, among them 17 were correctly diagnosed by FNAC (68%), eight by microbiological methods (32%) and 24 by PCR (96%). When PCR is considered the gold standard, FNAC predicted the correct diagnosis in 62% of cases with a high false negative rate (38%) due to the absence of granuloma/necrosis in smears from cases of early tuberculosis. In the latter group PCR proved to be the most valuable and a diagnostic success of 100% was achieved when FNAC and PCR were combined. In addition, PCR allowed immediate characterization of M. tuberculosis in the vast majority (96.2%) of cases in the study population.     

Possible errors in quantitative determination of phenylalanine ammonia-lyase activity by spectrophotometric methods

A possible error in spectrophotometric determination of cinnamate, the product of phenylalanine ammonia-lyase activity, using nonpurified protein extracts has been shown.     

Comparative study of methods for the quantitative assessment of the C-segment size of human chromosomes

The possibilities of comparison and reproducibility of results of estimation of the absolute dimensions of chromosomal C-segments measured by different methods have been studied. The data obtained indicate good comparability of the results obtained by all the methods in a definite range of chromosome condensation. All the methods demonstrated satisfactory reproducibility of the results on chromosomes 1 and 9. The errors of the quantitative estimation of chromosome 16 in the coupled cultures is discussed in view of the artefact nature of C-segment size variability.     

Comparative study of turbulent solid-liquid extraction methods for the determination of organochlorine pesticides

The aim of any extraction method in analytical chemistry is to effectively separate the analytes from the matrix with minimal solvent and time required. In this study, a comparison of the classical Soxhlet extraction and some new turbulent solid-liquid extraction techniques, such as fluidized-bed extraction (FBE), modified dive-in fluidized-bed extraction (dive-in FBE), modified dive-in Soxhlet extraction (dive-in SE) and dive-in thimble extraction (dive-in TE) for the determination of organochlorine pesticides (OCPs) was carried out. The turbulent extraction methods were performed by using the fexIKA vario control series extractor and by modification of the extraction system to dive-in technique, respectively. In addition, FBE and dive-in FBE were operated under the same, only for the FBE system established, optimum conditions. For the determination of the analytes a selective clean-up of the extracts followed by a gas chromatography (GC) method with mass spectrometric detection was used. All advanced extraction methods with reduced time and solvent consumption exhibited higher extraction efficiency than the standard procedure, Soxhlet extraction.     

Comparative chemical anatomy of the brain: concepts and methods

The study of neuropeptides represents an appropriate playground for comparative and evolutionary research. Comparative analysis can give insight into the conservative pattern of intercellular transmission molecules, possibly bound both to some evolutionary antiquity and to cellular constraints. In the same time it can teach us how modulation has occurred at molecular, cellular, multicellular levels in order to give the species-specific functional organization. Using some examples from vertebrate central neurons system (CNS) immunocytochemical analyses, the results so far obtained suggest the rise of a new comparative chemical neuroanatomy. The rationale of "what" and "why" we are comparing is, however, needed in order to understand constancy, heterogeneity or else trends toward complexity in the distribution of neuropeptides.